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Boxer54, Toyota Technician
Category: Toyota
Satisfied Customers: 1755
Experience:  ASE Master tech with L1 certification, Toyota Master Diagnostic Technician
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Prius: I have a Prius 2011 and want to fit automatic headlights.

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I have a Prius 2011 and want to fit automatic headlights. Do I just need to change the lights stalk to one with the 'auto' position as the car already has light sensor capability.
Thank you for trusting us with your Toyota question. There is much more involved with this installation than you think. All these functions work through the body ecu and integration relay which will both need to he replaced. It's also possible some wiring harnesses may need to be replaced. How much are you willing to spend on this?
Customer: replied 4 years ago.

If as you say I'd need to replace ECU & relays then what about using a conversion system such as a DEI545T unit to facilitate auto headlights. What wires would I need to tap into.

I have no idea what that is, can you post a URL so I can look at it?
Customer: replied 4 years ago.
Personally, I have never seen one of these units. Without having the instructions in front of me to look at, I couldn't begin to tell you where to wire it in. What I can advise is to get a professional installer to install it. That way, the burden is on them for a proper installation.

That having been said, and with no knowledge of this unit or how it connects, I would be very careful of this in your vehicle. Since we will be dealing with computerized functions on this vehicle, there is the possibility of some unwanted issues. There is a high speed data network connecting the various computers in this vehicle, so, any disruption can cause issues in other systems.
Customer: replied 4 years ago.
Here's a link to the wiring diagram:

What do you think.
Give e a bit to look over this information.
Here's where this will be a problem. Each wire coming out of the light switch does multiple functions. It is a ground sided circuit and each wire actually tells the body computer what is wanted via varied resistance based on the different positions. The unit you are looking at won't work with this system. You may try it and get limited functionality, or based on how it works, it could change the wiring resistance enough that you get totally unwanted functions. Overall, not a good idea in my opinion.
Boxer54, Toyota Technician
Category: Toyota
Satisfied Customers: 1755
Experience: ASE Master tech with L1 certification, Toyota Master Diagnostic Technician
Boxer54 and other Toyota Specialists are ready to help you
Customer: replied 4 years ago.

In your response you have described the resistance ladder network that enables the steering wheel controls to be recognised so the corresponding switch is correlated to the resistance relating to an individual steering wheel control. The light switch does not operate in this way as it is hard wired to the light control stalk. I thus lost faith in your response above and feel I'd be better off talking to an Auto Electrician with access to the Prius wiring diagram.

The light switch does multiple functions via varying resistance through only 2 wires(for the headlights) through the body ECU. This is from the wiring diagram, which I studied closely looking for a way to install the system you wanted. I am a Toyota master and Hybrid certified and I never mentioned anything about steering wheel controls.

Hello, and thank you for choosing Just Answer to help you with your questions!

I do agree that I would not recommend the nite lite system. They tend to be finicky and don't always work real well. But I've also installed them and have them work perfectly fine. The solar sensor is sub par if you ask me, that tends to be most of the cause of problems.

However, you CAN install it and have it "probably" work fine in your Prius. Any inconsistencies would be due to the solar sensor, NOT your Prius. Your headlight circuit is pretty simple, ground the parking light wire and the parking lights turn on. Ground the headlight wire and they turn on. There is no variable resistance circuit for these systems.

Installation would be pretty straight forward, through I would recommend a professional installation.

If you would like me to get detailed wiring connection information I can do that, however due to the nature of the Prius and with the lack of readily available power sources with enough current capacity to safely run the system, it may be a little tricky, and you may have to extend wiring to make it reach where it needs to go.
Customer: replied 4 years ago.

Hi Toyota Tom

Thank you for your answer above and it is perfectly satisfactory. Had I had a straight aswer like yours from the other guy I would have been more than satisfied. The only reason I didn't completed the "Rate to Finish" tab is that it told me I'd be up for yet another $22. Since I'd already parted with $22 already to the previous guy I've elected to reply to you and let you know what I thought. Not sure where to go from here to finish this off with out yet more expence.

Cheers and have a great 2013.



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